The reintroduction of small amounts of exhaust gases into the combustion cycle of an internal combustion engine to reduce the generation of nitrous oxides is known. It is also known that if the recirculated exhaust gases are cooled, further reductions in generation of nitrous oxides is experienced and fuel of lower octane can be used. In addition, if the recirculated exhaust gases are cooled the valve controlling the flow of exhaust gases has greater durability. It is, therefore, an object of this invention to cool the recirculated exhaust gases to achieve the advantages recited above. It is also an object of this invention to moderate the temperature of the recirculated exhaust gases to permit more accurate metering of the recirculated gases because of their more nearly uniform densities. It is the further object of this invention to provide an intake manifold having a heat exchanger contained in normally wasted space of a V-type internal combustion engine. It is an additional object of this invention to greatly reduce the number of connections from known recirculated exhaust gas cooling systems, and consequently, to reduce the number of potential leaks in the system. Finally, it is an object of this invention to provide an integral intake manifold and exhaust gas recirculation system which is economical to manufacture and which is generally more durable and reliable than prior art apparatus.
The invention comprises an intake manifold for supplying fuel, air and exhaust gases to a V-type multicylinder internal combustion engine having combustion chambers disposed along opposite sides of the longitudinal centerline. The manifold comprises a casting having one or more generally vertical riser passages and one or more generally horizontal plenum chambers in communication with the riser bores. A plurality of runner passages extends generally transversely from the plenum chambers. An exhaust gas crossover passage extends transversely under the plenum chambers and beneath the riser passages. An exhaust gas recirculation passage extends longitudinally from the exhaust gas crossover passage to a means for receiving a gas recirculation control valve constructed to meter the flow of the exhaust gas through the exhaust gas recirculation passage. A metered exhaust gas passage extends from the valve receiving means back to the riser passages. A heat exchanger is positioned in the exhaust gas recirculation passage and includes a longitudinally extending liquid conduit having finned elements extending radially outwardly therefrom. An engine coolant passage is formed within the manifold. The heater exchanger conduit forms a portion of the coolant passage. Seal means separate the conduit from the exhaust gas recirculation passage to define an independent coolant passage and an independent exhaust gas recirculation passage in heat exchange relationship.